The present invention relates to a polypyrrole film and a method of producing the same.
A method of synthesizing polypyrrole film is reported in J. Chem. Soc., Chem Comm., 1979, 635.
Further, with respect to polymerization of pyrrole, it is reported by K. C. Khulbe and R. S. Mann in J. Polym. Sci.: Polym. Chem. Ed. Vol. 20, pages 1089 to 1095, 1982, that pyrrole can be polymerized in an aqueous solution in the presence of potassium persulfate. The polypyrrole obtained by this method is in the form of powder.
In Japanese Laid-Open Patent Application No. 59-226020, there is described a method of electrochemically polymerizing pyrrole in an aqueous organic solvent in the presence of organic sulfonic acids. In the aqueous organic solvent employed in this method, at least 50 wt. % of water is contained. It is preferable to use only water in view of the cost and safety in the polymerization for industrial purpose.
In J. Am. Chem. Soc. Vol. 106, pages 6861 to 6863, 1984, it is reported by Baruch Zinger and Larry L. Miller that polypyrrole is obtained by anodic oxidation in an aqueous solution by using ferrocyanide ion (Fe(CN).sub.6.sup.4-) as dopant.
Although several methods of preparing such electroconductive polypyrrole films are known, a method of obtaining a self-standing polypyrrole film in an aqueous solution, which can be easily peeled off the anode for anodic oxidation, has not been reported yet.
Other electroconductive polymer films, such polythiophene, polyfuran, polyazulene, poly p-phenylene, and polyaniline films, are reported in the following references: Polythiophene and polyfuran in J. Electroanal. Chem., 135, 173(1982), polyazulene in IBM. J. Res. Develop., 27, 330(1983), poly p-phenylene in J. Chem. Soc., Chem. Comm., 1984, 1199, and polyaniline in J. Electroanal. Chem. 111(1980).
Recently many trials of using these electroconductive films, for instance, as the materials for electronics equipment are conducted. In the course of such trials, there is a great demand for large-size electroconductive polymer films. However, it is difficult to prepare an electroconductive polymer film having an uniform thickness and a large size by electrochemical polymerization. In the case of a polypyrrole film prepared by electrochemical polymerization, the maximum size so far obtained is about 20 cm.times.20 cm. It is extremely difficult to obtain a polypyrrole film larger than this size by the conventional methods.